BACKGROUND Ovine footrot caused by Dichelobacter nodosus (D nodosus) is an infectious disease affecting sheep worldwide. Switzerland plans a nationwide footrot eradication program, based on PCR-testing of interdigital swab samples. The aim of this study was to test for the presence of D nodosus in clinically footrot-free sheep flocks which had been subjected to different treatment strategies, to assess whether they were feasible for the eradication process, especially focussing on antimicrobial flock treatments. Clinical scoring and PCR-results were compared. Ten farms had used hoof bathing and hoof trimming without causing bleeding, ten had used individual treatments and flock vaccines to gain the free status and ten had become free through whole-flock systemic macrolide treatment. For every farm, three risk-based collected pool samples were analysed for the occurrence of virulent and benign D nodosus by PCR detection of aprV2/aprB2. RESULTS Six flocks from any treatment group tested positive for aprB2 in all pools. Clinical signs were absent at the time of sampling, but some flocks had experienced non-progressive interdigital inflammation previously. Two flocks tested aprV2-positive in the high-risk pool. One of them underwent a progressive footrot outbreak shortly after sampling. Individual retesting indicated, that virulent D nodosus most likely was reintroduced by a recently purchased ram. In the second flock, a ram was tested positive and treated before clinical signs occurred. CONCLUSIONS All treatment strategies eliminated the causative agent and were found to be suitable for implementation in the PCR-based eradication process. PCR-testing proved to be more sensitive than visual scoring, as it also detected clinically healthy carriers. It will be of benefit as a diagnostic tool in elimination and surveillance programs.

中文翻译：

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在临床上无脚臭的羊群中结节双歧杆菌的流行：消除策略的比较田间研究。

背景技术由结节性双歧杆菌（D.nodosus）引起的绵羊脚腐病是一种感染性疾病，其影响全世界的绵羊。瑞士计划基于叉指拭子样品的PCR测试，在全国范围内根除脚臭。这项研究的目的是测试在临床上无脚腐病的羊群中D结节的存在，这些羊群经历了不同的治疗策略，以评估它们是否可用于根除过程，特别是侧重于抗菌羊群治疗。比较临床评分和PCR结果。十个农场使用了蹄浴和修蹄术而不会造成出血，十个农场使用了单独的治疗方法和羊群疫苗以获取自由身分，十个农场通过全群系统大环内酯类药物治疗而变得免费。对于每个农场 通过PCR检测aprV2 / aprB2，分析了三个基于风险的收集池样品中有毒和良性D型结节的发生。结果来自任何治疗组的六只鸡群在所有库中的aprB2检测为阳性。采样时没有临床体征，但一些鸡群以前曾经历过非进行性指间炎症。高风险库中有两只鸡群的aprV2阳性。采样后不久，其中一人就进行了渐进性足癣暴发。个别重新测试表明，最近购买的公羊最有可能重新引入了强力D结节菌。在第二批羊群中，公羊经测试呈阳性并在出现临床体征之前进行了治疗。结论所有治疗策略均消除了病原，并被认为适合在基于PCR的根除过程中实施。PCR检测比视觉评分更敏感，因为它也检测出临床上健康的携带者。作为消除和监测计划中的诊断工具，它将很有用。